en Pathology Pathology case report case report <span style="font-size:14px;"><span style="font-family:Times New Roman;"><span style="color:#0000ff;"><strong><em>Background</em></strong><em>:</em></span> Mucinous cystadenocarcinoma is a relatively uncommon histological subtype of breast cancer that is a cystic form of papillary mucinous carcinoma. &nbsp;It is regularly negative for estrogen and progesterone receptors and it is most often diagnosed in older than 55-60 years old.&nbsp;The incidence of breast mucinous cystadenocarcinoma is about 1-6% of primary breast cancers. Here, we present a case of breast mucinous cystadenocarcinoma of left breast in a 69-year-old female which is positive for estrogen and progesterone receptors.<br> <span style="color:#0000ff;"><strong><em>Case Presentation</em></strong><em>:</em></span> In this article, we describe a case of a-69-year-old female with a painful mass in her left breast. Based on intraoperative pathology consult, neoplastic tissue mostly floating in mucinous lakes with invasion to surrounding stroma was seen. Immunohistochemistry profile showed positive estrogen and progesterone receptors and negative for HER2.<br> <span style="color:#0000ff;"><strong><em>Conclusion</em></strong><em>:</em> </span>Mucinous cystadenocarcinoma of breast is typically triple negative for hormone receptors. But ER and PR positive variant of this tumor is rare, giving the chance of a better prognosis for the patient with hormonal therapy.</span></span> Breast cancer, Mucinous cystadenocarcinoma, estrogen receptor, progesterone receptor 444 446 http://caspjim.com/browse.php?a_code=A-10-1716-1&slc_lang=en&sid=1 Ghodsieh Kamrani Gh.kamrani@gmail.com 100319475328460031225 100319475328460031225 No Department of Pathology, Cancer Research Institute, Babol University of Medical Science, Babol, Iran Novin Nikbakhsh novinsu@hotmail.com 100319475328460031226 100319475328460031226 No Department of surgery, Cancer Research Institute, Babol University of Medical Sciences, Babol , Iran Akram Hosseini Dr_Hosseini_2000@yahoo.com 100319475328460031227 100319475328460031227 No Department of Pathology, Cancer Research Institute, Babol University of Medical Science, Babol , Iran Hossein Ghorbani Hs.ghorbani@mubabol.ac.ir 100319475328460031228 100319475328460031228 No Department of Pathology, Cancer Research Institute, Babol University of Medical Science, Babol , Iran Niloufar Arefisigaroudi Nas.arefi@gmail.com 100319475328460031229 100319475328460031229 Yes Department of Pathology, School of medicine, Babol University of Medical Sience, Babol, Iran Ali Davarian Alidavarian@gmail.com 100319475328460031230 100319475328460031230 No Ischemic Disorders Research Center, Golestan University of Medical Science, Gorgan, Iran